What is group autofocus and what is it good for?

Started Apr 28, 2016 | Discussions
BigDG Forum Member • Posts: 90
What is group autofocus and what is it good for?

I don't understand what the purpose of group autofocus is. Page 104 of the manual states, "choose for subjects that are difficult to focus using a single focus point."  That doesn't tell me what the camera is doing.

Does the camera average the four points that are highlighted in red in the viewfinder?  Or does it pick the closest one of the four.  Or does it look for faces among the four points?  If there are two faces does it pick one or average the focus or what?

I'm mostly a street photographer trying to understand my new camera.

David

Warpdrv Regular Member • Posts: 172
Re: What is group autofocus and what is it good for?
3
 Warpdrv's gear list:Warpdrv's gear list
Nikon D7000 Nikon D500 Nikon AF-S DX Nikkor 35mm F1.8G Nikon AF-S Micro-Nikkor 60mm F2.8G ED Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II +2 more
luxun54 Senior Member • Posts: 1,133
Re: What is group autofocus and what is it good for?
2

BigDG wrote:

I don't understand what the purpose of group autofocus is. Page 104 of the manual states, "choose for subjects that are difficult to focus using a single focus point." That doesn't tell me what the camera is doing.

Does the camera average the four points that are highlighted in red in the viewfinder? Or does it pick the closest one of the four. Or does it look for faces among the four points? If there are two faces does it pick one or average the focus or what?

I'm mostly a street photographer trying to understand my new camera.

David

I had been wondering about this as well the other day, then found another thread here that recommended this article that explains the autofocus modes and when to use them. [Apparently, this original version of the article was updated after publication specifically to add the discussion of Group Autofocus when that mode was introduced a couple of years ago.]

 luxun54's gear list:luxun54's gear list
Nikon D300 Nikon D500 Nikon AF-S DX Nikkor 12-24mm f/4G ED-IF Nikon AF-S Nikkor 24-70mm f/2.8G ED Nikon AF-S Nikkor 80-400mm f/4.5-5.6G ED VR
DualSystemGuy Contributing Member • Posts: 622
Explanation
1

BigDG wrote:

I don't understand what the purpose of group autofocus is. Page 104 of the manual states, "choose for subjects that are difficult to focus using a single focus point." That doesn't tell me what the camera is doing.

Does the camera average the four points that are highlighted in red in the viewfinder? Or does it pick the closest one of the four. Or does it look for faces among the four points? If there are two faces does it pick one or average the focus or what?

I'm mostly a street photographer trying to understand my new camera.

David

Group AF is essentially a closest subject priority mode, it works incredibly well, especially on busy backgrounds. It really shines for things like BIF, motocross, auto racing, air shows, etc. and it's extremely fast.

Where it isn't as good, is if you need to pick out small details, or if the subject is filling a large portion of the frame already, since there is no way to precisely determine what it focuses on in those situations.

The camera groups 5 AF points together, and the middle one is still active even though it's not visible. It uses all 5 points to find the closest subject, basically, and stay locked on it. Group AF also works with face detection but only in certain modes. For street photography I wouldn't be using group, personally - it's very much geared toward action, but that isn't a rule obviously. Depending on the situation I love group AF, it really is a standout feature IMO.

 DualSystemGuy's gear list:DualSystemGuy's gear list
Sony RX100 VII Canon EOS-1D X Nikon D810 Canon EOS 7D Mark II Nikon D850
ViragSharma Junior Member • Posts: 45
Re: What is group autofocus and what is it good for?

Thanks ..tfs

BillyBobSenna
BillyBobSenna Senior Member • Posts: 2,092
Re: Explanation

DualSystemGuy wrote:

BigDG wrote:

I don't understand what the purpose of group autofocus is. Page 104 of the manual states, "choose for subjects that are difficult to focus using a single focus point." That doesn't tell me what the camera is doing.

Does the camera average the four points that are highlighted in red in the viewfinder? Or does it pick the closest one of the four. Or does it look for faces among the four points? If there are two faces does it pick one or average the focus or what?

I'm mostly a street photographer trying to understand my new camera.

David

Group AF is essentially a closest subject priority mode, it works incredibly well, especially on busy backgrounds. It really shines for things like BIF, motocross, auto racing, air shows, etc. and it's extremely fast.

Where it isn't as good, is if you need to pick out small details, or if the subject is filling a large portion of the frame already, since there is no way to precisely determine what it focuses on in those situations.

The camera groups 5 AF points together, and the middle one is still active even though it's not visible. It uses all 5 points to find the closest subject, basically, and stay locked on it. Group AF also works with face detection but only in certain modes. For street photography I wouldn't be using group, personally - it's very much geared toward action, but that isn't a rule obviously. Depending on the situation I love group AF, it really is a standout feature IMO.

Group did not work well for me for Motorsports. The ground would get picked up since it was closest.

 BillyBobSenna's gear list:BillyBobSenna's gear list
Nikon D500 Nikon D850 Nikon Z6 Nikon AF-S Nikkor 14-24mm f/2.8G ED Nikon AF-S Nikkor 24-70mm f/2.8G ED +11 more
calson Veteran Member • Posts: 9,839
Re: Explanation

Group AF provided me with no gain in AF performance with my D750 but with the D500 it enabled me to track fast moving hummingbirds and lock onto them with 100% accuracy which I found amazing.

For street photography I will prefocus on something to get the approximate range to a subject where I do not want them to react to me and the camera and freeze up or alter their behavior. With other cameras the single point AF-C was what I used. With the D500 there would be the option of using 3D AF mode to track a moving subject for a picture.

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